Sputtered Tb/FeCoTi multilayered films for magneto-optical recording

The magnetic properties of Tb/FeCoTi multilayered films, prepared by two-source DC magnetron sputtering, have been investigated as a function of the layer thickness to improve the recording sensitivity of magnetooptical disks. For a fixed bilayer thickness ratio, the Curie temperature, T_c, was strongly dependent on the Tb layer thickness and reached a maximum near 4 Å. The Kerr rotation θ_k is almost constant, independent of the Tb layer thickness. The effective composition shifts to the transition-metal-rich side with increase in Tb layer thickness, greater than 4 Å, made possible a pronounced reduction in T_c and effective composition adjustment, without decreasing θ_k. Studies on recording characteristics revealed that recording sensitivity and bias magnetic fields are controlled by the Tb layer thickness, without sacrificing carrier-to-noise ratio